Knitted elastic fabric and method for producing the same



March 2s, 1944. s, C, ILLEY ETAL 2,345,055

RODUCING THE SAME Y Original Filed June 11, 1942 v v v v v v A v A v v v l v l l v l l l Y A Y l Y A A Y U.

l A l Y A .I

I Y l Y A U I A' l A A Y l A A U IF'aiente'd Mar. 28, i944 iii KNTTED ELASTEC FREI() AND METHOD FOR PRDUSNG THE SAME Originali application .inne il.,A 1942, Serial No. 446,580. Divided and this application May 13, 1943, Serial No. 486,763

Claims.

The present invention relates to improvements in knitted elastic fabrics in which elastic strands of rubber or its equivalentv are combined with interknitted relatively-inelastic strands. The present application constitutes a division of our co-pending application Serial No. 446,580 filed June 11, 1942 and, like the same, is based on the disclosure of our now-superseded application Serial No. 376,438 flied January 29, 1941.

One of the objects of the present invention is to provide a superior knitted elastic fabric in which the elastic strands incorporated therein are attached to the relatively-inelastic strands of the knitted fabric in such manner as to guard against the creepage or run-back of the said elastic strands relative to the inelastic strands, in the event that the said elastic strands should become severed.

Another object of the present invention is to provide a superior method for producing knitted elastic fabrics in which the elastic strands are gripped against relative slippage in the fabric and whereby the knitting operation may be carried to completion without requiring the employment of adhesives which interfere with the functioning of knitting machinery.

A further object of the present invention is to provide a superior method whereby a knitted elastic fabric may be readily knitted without special handicap and whereby following the knitting operation, the fabric may be subjected to a step which will effectively grip the elastic strands to the remaining relatively-inelastic portions of the knitted fabric.

With the above and other objects in view, as will appear to those skilled in the art from the present disclosure, this invention includes all features in the said disclosure which are novel over the prior art and which are not claimed in any separate application.

In the accompanying drawing, in which certain modes of carrying out the present invention are shown for illustrative purposes:

Fig. 1 is a schematic face view of a fragment of a knitted elastic fabric produced in accordance with the present invention and showing vthe said fabric prior to the same being subjected-to the heat-treatment of its heat-shrinkable gripping-strands; and

Fig. 2 is a view corresponding to Fig. l but schematically showing the fabric subsequent to its being heat-treated.

In the accompanying drawing is shown a knitted elastic fabric which includes two later y said strands ally-spaced-apart parallel elastic strands liliii which may be of round, rectangular or other suitable cross-sectional form and which maybe composed of rubber or other suitable elastic material. The said elastic strands ill-I0 or their equivalent may be individually covered by wrappings or the like, as is well known inthe elasticfabric art, or the said elastic strands may be bare as shown.

The elastic fabric also includes a -plurality of relatively-non-elastic strands Il interknitted in the fabric in the areas intermediate the elastic strands Ill- I0 and in the areas on the outer. sides thereof. The said relatively-nonelastic strands Il may be composed of any suitable textile material such, for instance, as cotton, regenerated cellulose, silk, Wool, etc., and when in place in the fabric they follow a sufficiently undulatory or serpentine path to thereby permit the fabric to be stretched against the tension of the elastic strands illl0 or their equivalent.

Extending substantially helically around and hence substantially crosswise of each of the elastic strands Iii-lil is one (or more) gripping-strands I2 formed of heat-shrinkable material either in whole or in part. In Fig. 1 the I2 are shown in their heatshrinkable condition, whereas in Fig. 2 the said strands are shown after having been thermally shrunk or contracted. The aforesaid heatshrinkable gripping-strands `I2 are formed either in whole or in part of heat-shrinkable artificial resin or resins and extend crosswise of the complemental one of the elastic strands ill-i0 into interknitted relationship with respect to, the relatively-non-elastic strands II on both sides thereof. As before noted, the

hieat-shrinkable gripping-strands I2 or their equivalent may be formed entirely of heatshrinkable artificial resins or partly thereof, the requirement being that the complete grippingstrand be inherently capable of being shrunk by heat to effect a binding or anchoring effect, as will hereinafter be described.

The heat-shrinkable gripping-strands i2 or their equivalent may be twisted or untwisted and formed, for instance, wholly or in part of a co-polymer of vinylacetate and vinylchloride, polyamides, vinylidenechloride or the like. Preferably, however, heat-shrinkable artificial resin strands, threads or ribbons are formed by the well-known stretch-spinning process or by a process involving stretching subsequent to spinning.

In the particular fabric shown in the accompanying drawing, the given heat-shrinkable gripping-strand I 2 adjacent a given elastic strand Ill extends completely around the said elastic strand though interknitted at each side of the latter with the relatively-non-elastic strands Il.

Instead of knitting the gripping-strands i2 around the elastic strands I0, the said elastic strands may be drawn into position after the fabric has been knitted, though the latter practice is not preferred over the former.

After the various strands ill, Il and l2 or their equivalent have been fabricated as illustrated schematically in Fig. 1, the knitted fabric may be subjected to a heating operation either while wet or dry, to a temperature above the softening point of the artificial-resin gripping-strands i2 to thereby cause the said strands to contract. The temperatures and the periods of exposure to such We claim:

1. A method for producing knitted elastic tabrics which includes: fabricating together a plurality of laterally-spaced-apart elastic strands and a plurality of interknitted relatively-inelastic strands including a plurality of heat-shrinkable gripping-strands of artificial resin: at least one of the said heat-shrinkable gripping-strands having a multiple number of reaches extending crosswise of a given elastic strand and interknitted on the v respective opposite sides thereof with other relatemperatures may vary widely and in most in- I stances variations in temperature and/cr times of be in the order of to 40% contraction. It will be understood that relatively-thin and light-- weight fabrics require less time of exposure to heat than the thicker heavier fabrics such, for

instance, as multi-ply fabrics.

The heat-treatment above referred to will cause the gripping-strands l2 to contract suinciently to squeeze the elastic strands Ill-I0 and the interknitted portions of the relatively-non-elastic strands Il, as is shown in Fig. 2. The result of the shrinkage just referred to will be to cause the elastic strands to be anchored or clamped to the relatively-non-elastic strands I I at repeated closely-spaced intervals along the lengths of the said elastic strands. Thus, should a given elastic strand I0 or its equivalent besevered, it will be held against creeping or retraction in the knitted fabric beyond predetermined limits.

It is to be noted that after the gripping-strands l2 have been thermally shhmk, they extend substantially helically around their complementa] elastic strands III so that the sald elastic strands may be stretched without appreciable restraint by the said heat-shrinkable strands, since the convolutions of the latter will merely steepen their respective pitches as the said elastic strands are stretched.

In knitting fabrics, a given strand may be knitted back and forth in manners well understood in the art, though since each reach may independently follow its prescribed knitted path,

the fabric may be properly regarded, for instance..

as incorporating a plurality of relatively-nonelastic strands such, for instance, as those designated by the reference character Il or I2 or combinations thereof.

The invention may be carried out in other speciilc ways than those herein set forth without departing from the spirit and essential characteristics of the invention, and the present embodiments are, therefore, to be considered in all respects as illustrative and not restrictive, and all changes coming within the meaning and equivalency range of the appended claims are intended to be embraced therein.

tively-inelastic strands occupying the spaces between the laterally-spaced-apart elastic strands; and then subjecting the heat-shrinkable grippingstrands to the action of heat to cause the same to contract to grip the said elastic strands and couple the same to the knitted fabric with a high degree of resistance to longitudinal slippage with respect thereto.

2. A method for producing knitted elastic fabrics which includes: fabricating together 'a piurality of laterally-spaced-apart elastic strands and a plurality of interknitted relatively-inelastic strands including a plurality of heat-shrinkable gripping-strands of artificial resin; at least one of the said heat-shrinkable gripping-strands extending substantially helically around a given elastic strand and interknitted on the respective opposite sides thereof with other relatively-,inelastic strands occupying the spaces between the laterally-spaced-apart elastic strands: and then subjecting the helically-disposed heat-shrinkable gripping-strands to the action of heat to cause the convolutions thereof to grip the said elastic strands and couple the same to the knitted fabric with a high degree of resistance to longitudinal slippage with respect thereto. l

3. A method for producing knitted elastic fabrics which includes: fabricating together s plurality of laterally spaced apart elastic strands, a plurality of interknitted relativelyinelastic and relatively non-heat shrinkable strands, and a plurality of heat-shrinkable gripping-strands of artificial resin, the last two mentioned pluralities of strands being interknitted with each other; at least one of the said heatshrinkable gripping-strands having a multiple number -of reaches extending crosswise of a given elastic strand and interknitted on the respectilve opposite sides thereof with the interknitted strands occupying the spaces between the laterally-spaced-apart elastic strands; and then subjecting the heat-shrinkable grippingstrands to the action of heat to cause the same to contract to grip the said elastic strands and couple the same to the relatively-inelastic and relatively-non-heat-shrinkable interknitted strands of the knitted fabric with a high degree of resistance to longitudinal slippage with respect thereto.

4. A method for producing knitted elastic fabrics which includes: fabricating together a plurality of laterally-spaced-apart elastic strands, a plurality of interknitted relatively-inelastic and relatively-non-heat-shrinkable strands, and a plurality of heat-shrinkable gripping-Siirnds 0f artificial resin, the last two mentioned pluralities of strands being interknittted with each other; at least one of the said heat-shrinkable gripping-strands extending substantially helically around a given elastic strand and interknitted on the respective opposite sides thereof with the interknitted strands occupying the spaces between the laterally-spaced-apart elastic strands; and then subjecting the helically-disposedrheatasuma of heat-shrinkable gripping-strands of artificial resin; at least one of the said heat-shrinkable elastic strands; a plurality of interknitted relatively-inelastic and relatively-non-heat-shrinkable strands; and a plurality of heat-shrinkable gripping-strands of artificial resin; the last two mentioned pluralities of strands being interknitted with each other; at least one of the said heatshrinkable gripping-strands having a multiple number of reaches extending crosswise of a. given elastic strand and interknitted on the respec- 10 tive opposite sides thereof with the interknitted grippinggstrands having a multiple number of reaches extending crosswise of a given elasticV strand in binding relationship thereto and interknitted on the respective opposite sides thereof with other, relatively-inelastic strands occu- Dying the spaces between the laterally-spacedapart elastic strands; the said heat-shrinkable strands occupying the spaces between the laterally-spaced-apart elastic strands; the said heat-shrinkable gripping-strands being thermally contracted in situ into gripping engagement u with the said elastic strands to couple the latter gripping-strands being thermally contracted in 20 situ into gripping engagement with the said elastic strands to couple the latter to the knitted fabric with a high degree of resistance to longitudinal slippage with respect thereto.

6. An anti-creep knitted elastic fabric comprising: a plurality of laterally-spaced-apart elastic strands; and a plurality of interknitted vrelativelsr-inelastic strands including a plurality of heat-shrinkable gripping-strands of artificial resin; at least one of the said heat-shrinkable gripping-strands extending substantially helically around a given elastic strand and interknitted on the respective opposite sides thereof with other relatively-inelastic strands occupying the spaces between the laterally-spacedapart elastic strands: the helically-disposed convolutions of the said heat-shrinkable gripping-strands being thermally contracted in situ into gripping engagement with the said elastic strands to couple the same to the knitted fabric, with a high degree of resistance to longitudinal slippage with respect thereto.

7. An anti-creep knitted elastic fabric compricing: -a plurality of laterally-spaced-apart to the relatively-inelastic and relatively-nonheat-shrlnkable interknitted strands of the knitted fabric. with a high degree of resistance to longitudinal slippage with respect thereto.

8. An anti-creep knitted elastic fabric comprising: a plurality of laterally-spaced-apart elastic strands; a plurality of interknitted relatively-inelastic and relatively-non-heat-shrinkable strands; and a plurality of heat-shrinkable gripping-strands of artificial resin; the last two mentioned pluralities of strands being interknitted `with each other; at least one of the said heat shrinkable gripping-strands extending substantially helically around a given elastic strand and interknitted on the respective opposite sides thereof with the interknitted relatively-inelastic strands occupying the spaces between the laterally-spaced-apart elastic strands; the said heat-shrinkable gripping-strands being thermally contracted in situ into gripping engagement with the said elastic strands to couple the latter to the relatively-inelastic and relatively-non-heat-shrinkable interknitted strands of the knitted fabric, with a high degree of resistance to longitudinal slippage with respect thereto.

SAMUEL C. LILLEY. EDWARD E. FOSTER. 

